Compact low silhouette keyboard mechanism

ABSTRACT

A plural key keyboard having a parallelogram four-bar linkage which provides equal key dip for all keys irrespective of row or distance from the operator. The mechanism is very compact and the components are densely packed giving minimum dimensions from front to rear and top to bottom. Access to inner components is provided by means of a swing away subassembly which includes the key buttons and immediately associated linkage. Antirepeat and interlock features are provided. Provision is made for a selective keyboard lock. All keys are locked against depression when power is disconnected.

i United States Patent [72] Inventor Hugh St- Lawrence Dannatt 3,191,740 6/1965 Smusz etal 197/107 X R 'i 3,324,985 6/1967 Palmer et al.... 197/16 [21] Appl. No. 838,539 3,327,828 6/1967 Dannatt 197/16 X [22] Filed July 2,1969 3,339,695 9/1967 Palmer 197/16 X Patented Nov-2, 1971 3,348,648 10/1967 Frechette 197/16 [73] Assignee The Singer Company 3,379,297 4/1968 Jablonskiet al. 197/16 Primary Examiner-Robert E. Pulfrey [54] COMPACT ow SILHOUETTE KEYBOARD Assistant Examiner-Stephen C. Pellegrino MECHANISM Attorneys-George W. Killian and Samuel R.. Genoa 26 Claims, 5 Drawing Figs. [52] U.S.Cl 197/17, ABSTRACT: A plural key keyboard having a parallelogram 197/27' 197/106 197/107 four-bar linkage which provides equal key clip for all keys ir- [5 In. n

re pective of row or distance from the operator The 7/02B41J 5/14 mechanism is very compact and the components are densely [50] Field of Search 197/16, 18, acked giving minimum dimensions from front to rear and top 98, 103, 186 A, v 17; 235/145, 146 to bottom. Access to inner components is provided by means of a swin away subassembly which includes the key buttons [56] References Cited and imme diately associated linkage. Antirepeat and interlock UNITED STATES PATENTS features are provided. Provision is made for a selective 2,905,297 9/1959 Stuiber etal 197/17 keyboard lock. All keys are locked against depression when 2,966,249 12/1960 Israelson 197/17 power is disconnected.

PAIEmEuu'u'vz I97! 3.616.866

sum 18F 2 lnvenfor Hugh StLowrence Donna" y COMPACT LOW SILHOUETTE KEYBOARD MECHANISM BACKGROUND OF THE INVENTION The present invention relates to a keyboard and more specifically to a keyboard of the type which might be used in a typewriter, a calculator, a card punch or any similar device having a plurality of keys. In such devices, especially when they are required to provide signals to other devices, it is customary tohave an element known as a slide associated with each keylever. See for example my own U.S. Pat. No. 3,327,828, granted June 27, 1967, which discloses a slide 47 for each keylever 18. One common function of the slide is to cause the generation of a unique electrical output signal. In the cited patent this is done by selectively operating a unique group of a smaller plurality of bails. In a typewriter the signal might cause the activation of a selected typebar; or the mechanical motion of the slide could initiate an action which results in typebar operation.

Quite obviously, provision must be made to prevent having more than one slide away from its normal position at a time, for if more than one were off-normal, an improper and defective code would be generated. A device known as an interlock is normally employed to prevent more than one slide from being operated at a time. A wide variety of means for providing an interlock are well known by those skilled in the keyboard art.

Another problem that confronts the designer is that provision must be made to prevent repeat operations if a keylever is depressed and held down. A mechanism that prevents unwanted repeats is said to have an antirepeat feature.

A mechanism which provides all the required features is a rather complex mechanism and the complexity is increased by the fact that the entire structure must be housed in an arrangement that permits the manually operated keys to be conveniently located. For a variety of reasons, it has become desirable for the keyboard to have what is known as a low silhouette. That is, the distance between the key tops and the surface on which the machine is resting should be minimum. Some manufacturers have attempted to provide the desired low silhouette by having a substantial part of the machine or mechanism below the table surface. That is, a special table with a hole or well is used.

In keyboards, it is desirable to be able to have physical access to the slides and associated mechanism to permit cleaning, maintenance and repair; and in selected applications to permit code changes.

Typical prior art typewriter keyboards have all keys pivoted along a common line and therefore it is usual to have the keys having their key tops further from the said common line swing through a greater are in operating. This has been accepted as a necessary inconvenience although many patents have disclosed various techniques for providing equal key clip. However, for various practical reasons, none have gained wide acceptance. The present structure discloses a practical means for providing equal key dip and which also provides other substantial benefits.

It is an object of the present invention to provide a new and improved keyboard.

It is another object to provide a keyboard having a low silhouettc.

It is another object to provide a keyboard whose structure and assembly permits a simple and ready access to the inner parts.

It is another object to provide a keyboard having all the foregoing features and including conventional features such as an interlock and keyboard lock.

It is another object of this invention to provide a keyboard structure having a new and improved antirepeat mechanism.

It is another object of this invention to provide a keyboard wherein all keys have a substantially identical extent of travel irrespective of the row in which they are located.

It is another object of this invention to provide a keyboard having a selective keyboard lock for selectively locking out the operation of a predetermined group of keylevers.

THE DRAWINGS FIG. 1 comprises a view of a partially assembled keyboard showing a keylever and some associated components in their normal position and in their raised position.

FIGS. 2 through 5 show the relative positions of selected members of the structure at various stages of operation. More specifically:

FIG. 2 shows the relative positions of all parts with power applied and keylever up,

FIG. 3 shows the keylever depressed but the slide not yet moved,

FIG. 4 shows the slide in its active position, and

FIG. 5 shows the keylever still down and the slide in an intermediate restored position and out of the interlock.

ASSEMBLY AND OPERATION A preferred embodiment of a keyboard in which the invention is incorporated is illustrated in FIG. 1. The mechanism is assembled on a baseplate 101. Attached to the baseplate 101 is a bracket 102, and a similar bracket (not shown) is at the other end of the base plate 101. The bracket 102 may be attached to the baseplate 101 by any suitable means (not shown) such as machine screws or spot welding. The bracket 102 includesfirst and second upturned ears 103 and 104 and attached to each ear 103 and 104 are studs 105 and 106 to provide a pivot and guide, respectively. Ann 107 is pivotally coupled to stud 105, and a similar arm )(not shown) is pivotally coupled to (not similar stud and upturned car (not shown) at the other end of the baseplate 101. Connecting arm 107 and its unshown mate is bar 108. Attached to bar 108, by any suitable means is plate 109 which extends substantially from one arm 107 to the other. The forward edge of the plate 109 is made into a comb with the individual teeth 110 thereof shaped around and capturing a pivot rod 111.

Attached to the base plate 101 is a solenoid 112 having a plunger 113 coupled to an arm 114 which is fixed to a shaft 115. Accordingly, when solenoid 112 is electrically energized, plunger 113 is attracted towards the solenoid 112 and arm 114 follows but pivots about the centerline of shaft 115. Shaft 115 is rotationally supported by means, not shown, at its ends, thereby fixing it relative to the baseplate 101. Since arm 114 is coupled to shaft 115, the pivoting of the arm 114 by movement of plunger 113 results in angular rotation of shaft 115. Fixed to shaft 115 is arm 116 having stud 117. Link 118 is pivotally supported on stud 117 and slideably supported at guide stud 106. Accordingly, rotation of shaft 115 will result in a motion of link 118 which is principally in the longitudinal direction of link 118. An arm stud and link similar to members 116, 117 and 118, respectively, are also assembled in a similar fashion at the other end of baseplate 1101. However, it should be understood that there is only one solenoid 112. Link 118 (and its counterpart at the other end) is coupled to bail 119. The last-mentioned coupling may be achieved by any convenient means. Attached to the baseplate 101 is a post 120 and coupled between the post 120 and an upturned car 121 of bail 119 is a spring 122. Similar elements are provided at the other end. Accordingly, spring 122 and its unseen counterpart provide a bias that tends to rotate shaft 115 in a clockwise direction as seen from the sectioned end of FIG. 1. Thus spring 122 tends to keep plunger 113i withdrawn from solenoid 112. However, the energy of solenoid 112 is sufficient to overcome the force of spring 122 and thus actuation of solenoid 112 will be effective to move bail 119 towards the forward edge of the baseplate 101. The forward edge being that edge which is at the left in FIG. 1 and which is towards the operator when the keyboard is in normal position for use by an operator.

Extending along and attached to the forward edge of the baseplate 101 is a comb assembly 123 having teeth which are equal in spacing to that of the teeth and slots of the comb formed of the forward part of plate 109. A pivot rod 124 is assembled with comb assembly 123.

Coupled between pivot rods 111 and 124 is a linkage and therefore when arm 107 is raised and pivoted about pivot point 105 the linkage between rods 111 and 124 is displaced. To illustrate at least some of the various positions, the arm 107 is shown in a raised position together with a portion of plate 109 and pivot rod 111. In addition, a portion of plate 109, teeth 110 and rod 111 is shown in the position they assume when arm 107 is pivoted to its lowest position. In normal operation the arm 107 is pivoted down and the linkage between rods 111 and 124 is as shown in solid lines. A member of the linkage is shown in dotted lines to illustrate its position when am 107 is raised.

Ann 107 is pivoted to provide assembly access, maintenance and possible code modification. The downward pivoting of arms 107 is limited by stops, not shown mounted on baseplate 101.

Mounted on baseplate 101 is a spacer 125 and comb assembly 126, these parts being fixed relative to the base plate 101. The rear edge 127 of comb assembly 126 can serve as a stop limit the forward motion of bail 119 as edge 128 of bail 119 engages edge 127, or if desired other limiting means could be provided. For example, link 118 could have a pair of studs which engage post 120 and thereby limit the motion of link 118. Numerous other techniques could be employed. The portion of comb assembly 126 that extends rearward of spacer 125 is formed slightly up thereby creating a slight angle between the baseplate 101 and the described portion of comb assembly 126.

Captured between the baseplate 101 and the portion of comb assembly 126 extending rearward of spacer 125 is a contact operating bail 129. The forward edge 130 of contact bail 129 engages the rear edge of spacer 125. At each end of contact bail 129 is an upturned lug 131 (only one shown). Between the lug 131 and a post 132 supported on plate 101 is a spring 133. The spring 133 urges contact bail 129 to pivot counterclockwise as seen from the right-hand end of assembly of FIG. 1. The pivoting of bail 129 is limited by portion of the comb assembly 126 which extends rearward of spacer 125. An arm 134 of bail 129 is adapted to engage a contact set 135 which is appropriately mounted on base plate 101. The contact set 135 may comprise any desired contact configuration and will be actuated in response to the pivoting of contact bail 129 by a means to be more fully explained hereinafter.

The linkage between pivot rods 111 and 124 comprises rear link member 136, keylever link member 137 and front link member 138. Front and rear link members 138 and 137 pivot freely on their respective pivot rods 124 and 111. That is, the pivot rods do not need to rotate with their link members. Of course, it should be understood that there is a plurality of sets of links such as 136, 137 and 138 with one such set for each key button such as 139. That is, if the keyboard is associated with a printer such as typewriter there would be a number of key buttons and link sets corresponding to the number of keys on a conventional typewriter; while if the keyboard is associated with a calculator which accepts numeric information only, a lesser number of key buttons and links would be used. In order to open up the drawing and be able to show greater detail only one key button and link set is shown.

The keylever link member 137 is pivotally coupled to rear link member 136 by rivet 140; and is pivotally coupled to front link member 138 by rivet 141. A leaf spring 142 anchored under comb assembly 123 exerts an upward force at rivet 141. The upward limit of motion of rivet 141 is controlled by a bent over comb tine 143 of comb assembly 123 (see FIG. 2). The particular comb tine that engages and limits the shown rivet 141 is not shown in FIG. 1 as it would obscure other parts. However, a similar comb tine 143 is shown to the left of the illustrated set of links and a similar comb tine would exist over rivet 141. FIG. 2 also illustrates the effect of comb tine 143 in limiting the upward motion of link 138 as urged by spring 142. As may be seen from FIG. 1, or any of the other FIGS., the front and rear links 138 and 136 are nearly parallel to the base plate 101. A downward pressure on key button 139 would be opposed by spring 142 but sufficient pressure (which could be opposed by spring 142 but sufficient pressure (which could be by the force of spring 142) will result in a downward motion of keylever link 137 and the pivoting of the front and rear links 138 and 136, respectively. The resultant down position is shown in FIGS. 3, 4 and 5. Because rivets and 14] actually move in an are about their associated pivot rods 111 and 124 the keylever link 137 will actually have a very slight forward component of motion. However, the forward or longitudinal component of motion is so slight as to be imperceptible to an operator.

It should be observed that keylever link 137 may be constructed with supports for key buttons 139 at different points along the link 37 to thereby provide key buttons in various rows or distances from the front of the keyboard. It should be particularly noted that a given downward motion of key button 139 results in a corresponding downward motion of link 137 irrespective of the placement of the key button 139 along the link 137. Accordingly, all key buttons in all rows will have an equal dip. This is unlike the conventional typewriter wherein the keys near the operator must travel through a considerably larger stroke than the other keys.

Referring again to FIG. 1, there is another comblike assembly 144 which has captured therein pivot rod 145. In each comb slot there is a slide 146 having a longitudinal slot 147 through which pivot rod passes. The fixed pivot rod 145 and the slot 147 together with the comb assembly 144 limit the motion of the slide 146 to a limited rotational and longitudinal motion. Another comb structure 148 coupled to the baseplate 101 has teeth which also serve to restrict and guide slide 146. The forward edge of comb assembly 148 also has tines to which one end of a spring 149 is coupled while the other end of the spring 149 is coupled to slide 146, as shown. The spring 149 urges its associated slide in the forward longitudinal direction and in clockwise rotation about pivot rod 145 as viewed from the right-hand end of the keyboard. The clockwise rotation is limited by the interference of bearing area 150 of slide 146 with the bottom of the associated slot of comb structure 148.

The slides 146 engage a conventional ball interlock so that not more than one of the slides 146 may be pivoted counterclockwise (by a means to be hereinafter described) at a time. Balls comprise part of the interlock. The balls 160 are captured in another comblike structure, but almost none of the last-named structure shows in FIG. 1. However, the interlock is so conventional and widely used in the keyboard art that it is believed that a detailed illustration and description thereof is not necessary. Obviously, the interlock could be omitted if operating conditions do not require it. As will be evident to those skilled in these arts having the interlock associated with the slides 146 has advantages over an interlock associated with the keylever. However, if desired, the assembly could be modified to have the interlock associated with the keylever link 137.

The assembly as illustrated in FIG. 1 illustrates the relative positions of the identified parts with no key button depressed and without electrical power applied. In this condition, bail 119 is in a rearward position and extends under a lower forward edge 151 of slide 146. The upper forward edge 152 of slide 146 is positioned immediately below a slide-actuating ear 153 rigidly affixed to keylever link member 137. Accordingly, a downward motion of key button 139 will cause ear 153 to engage the upper forward edge 152 of slide 146 and urge a counterclockwise rotation of slide 146 about pivot rod 145. However, as will be noted in FIG. 1, such rotation of slide 146 will be impeded by bail 119. As will be more fully appreciated when the complete operation is comprehended, the impeding action just described will prevent the inadvertent tripping of a slide 146 while the machine is turned off and a consequent generation of an undesired code when the machine is turned on. In addition, bail 119 locks the keyboard against generation of a new code before completion of action on the prior code.

At the rear of baseplate 101 is a contact support member 154 having a plurality of contact members 155 all of which are insulated from each other and the support member 154. Below each of the plurality of contact members 155 is mating contact member 156. At the back end of each slide 146 are contact fingers 157 which are insulated from the slide 146 but are electrically connected together. Accordingly, when slide 146 is in its rearward longitudinal position, the upper contact finger comes into contact with the associated contact member 155; while the lower contact finger 157 comes into contact with the mating contact member 156. The result is that there is electrical continuity between a pair of contacts 155' and 156, through fingers 157. By this means, electrical signals may be generated which are unique to the actuated slide. Accordingly, as successive slides 146 are actuated, electrical signals will be generated. If desired, other contact means means, be used, for example, a microswitch could be actuated by each slide 146. Or, if desired, a plurality of bails could be employed somewhat as shown in my cited patent. One advantage of the illustrated technique is that contact members 155 and 156 may comprise printed circuit elements on support member 154 thereby providing an economical subassembly having a minimum of external wiring.

Having described the structure and assembly of a preferred embodiment of the invention, there will now be set forth a description of the action which obtains in response to actuation of a keylever. For this purpose reference will be had primarily to FIGS. 2 to 5 although the reader may also find it expedient to refer to FIG. I occasionally.

FIG. 2 illustrates the relative position of the various parts when power is connected and a key button 139 has not been depressed. More specifically, this means that bail 119 is in its forward position; or to the left in FIGS. 2 through 5. For convenience, the terminology of forward" and rearward" will continue in use in this description and of course relates to positions relative to the operator. With bail 119 in the forward position key button 139 may be depressed thereby causing the front and rear link members 138 and 136 to pivot about their respective pivot rods 124 and 111 and a corresponding downward motion of keylever link member 137. The slide actuation car 153 on link 137 will engage the upper forward. edge 152 of slide 146 and thereby rotate slide 146 about its pivot rod 145 in a counterclockwise direction. The slide 146 will enter the ball interlock and displace balls 160 to close the interlock and prevent the simultaneous entry of any other slide into the interlock. Continued depression of the key button 139 will result in the lower forward edge 151 of slide 146 engaging contact bail I29 and causing the last-named bail 129 to pivot slightly in a clockwise direction (see FIG. 3). The pivoting of bail 129 will result in actuation of contact set 135 by arm 134. In response to the actuation of the contacts 135 the circuit to the solenoid 112 will be opened and as a result shaft 115 will be pivoted and link 118 will move bail 119 rearward. The rearward motion of bail 119 will cause it to engage slide 146 at the front forward edge 158 thereof and cause the slide to move longitudinally to the rear (see FIG. 4). The shape of the rearward edge of bail 119 and the mating portion of slide 146 are such that they will remain engaged and slide 146 will remain pivoted against the force of spring- 149 even after there has been sufficient longitudinal motion of slide 146 to cause the upper forward edge 152 of slide 146 to become disengaged from ear 153. That is, although spring 149 exerts a clockwise pivoting torque on slide 146, there will not be sufficient torque to disengage slide 146 and bail 119. The subsequent forward motion of bail 119 will disengage bail 119 and slide 146 and said slide 146 will pivot clockwise in response to the torque of spring 149.

The rearward motion of slide 146 will cause contact finger 157 to complete an electric circuit between the contact members 155 and 156 associated with the specific slide 146 which moved rearward.

The rearward motion of slide 146 causes a disengagement between the lower forward edge 151 of slide 146 and contact operating bail 129. As a result bail 129 is pivoted back to its normal position by springs 133. With contact bail 129 restored to normal, the contacts of contact set will resume their former configuration. Depending upon the nature of the associated equipment and the extent of the electrical interlocks therebetween, the restoration of contact set 135 to normal may or may not result in the reoperation of solenoid 112. That is, in some circumstances it will be desirable to provide an electrical interlock whereby the associated equipment maintains an open circuit to solenoid 112 until the associated equipment has received and acted upon the electrical signal generated in response to the completion of an electrical circuit between contacts 155 and 156 corresponding to the operated slide. The use of such an electrical interlock will guarantee no lost codes and code storage and will prevent the generation of untimely new codes as with bail 119 in the rearward position no keylever can be depressed. Electrical interlocks are well known and the details thereof are not disclosed herein as such interlock does not form an integral part of this invention. The ultimate energization of solenoid 112 will result in bail 119 being moved forward, against the force of springs 122-and thereby open the keyboard to the generation of a new code.

With bail 119 in the forward position, spring 149 associated with slide 146 will cause slide 146 to move forward. In addition, spring 149 will exert a pivotal force on slide 146 and cause it to pivot clockwise and out of engagement with interlock balls 160.

With the slide 146 now in partialforward position, the contact fingers no longer engage contact members 155 and. 156 and the slide is not in the mechanical interlock. Accordingly, another key button 139 could be depressed to activate another cycle of operation and move another slide 146 even though the first depressed key button 139 had not been fully restored.

With the key button 139 still depressed, the front forward edge 158 of slide 146 will engage the rear of slide actuating ear 153 andprevent slide 146 from being urged to its full forward position by spring 149. It must be noted, however, that slide 146 is out of the mechanical interlock, that its fingers 157 are no longer making contact with contacts 155 and 156 and that it will not be engaged by a subsequent cycle of operation ofbail 119 (see FIG. 5).

When pressure isremoved from key button 139, spring 142 will apply an upward force to raise the link members 136, 137 and 138. With link- 137 raised ear 153 will be raised out of engagement with the front forward edge 158 of slide 146 and spring 149 will cause slide to move forward under car 153 until the slide 146 is limited in its forward motion by the engagement of the rearward part of slot 147 with pivot rod (see FIG. 2). It may be noted that ear 153 has a forward to rearward slope from top to bottom. The reason for this is to help slide 146 pivot clockwise in response to the force of spring 149 while the key button 139 is still down and the front forward edge 158 of slide 146 is engage-dtherewith. As the key button 139 is. raised, the slope of car 153 will tend to cam slide 146 slightly rearward. The extent of this cam action will not be sufficient to allow contact finger 157 to engage contacts or 156.

It should also be noted that ear 153 does not engage the upper forward edge 152 of slide 146 when the key button 139 is up. That is, there is to be a slight downward motion of ear 153 before it engages the slide 146. This relationship guarantees that the slide will be disengaged from car 153 and be allowed to move forward under ear 153 and be ready to be engaged in a subsequent cycle of operation.

The described action of slide 146 together with slide actuating ear 153 provides an antirepeat feature. That is, the prolonged depression of the keylever does not result in multiple code generations. Prior art antirepeat assemblies required a pivoted or moveable member on the keylever. See, for example, my earlier cited U.S. Pat. No. 3,327,828. in the present structure, the antirepeat feature is provided with a structure that includes a slide actuating car 153 which is fixed and immoveable relative to the keylever link member 137.

The present structure lends itself very nicely to the inclusion of a selective lock for selectively preventing the depression of selected key buttons 139. At the rear of link 137 there is a finger 159 which could be used to engage a selectively operated bail. Thus, for example, an alphanumeric keyboard could be arranged to selectively lock out all numeric keys. To this end, a bail with selectively positioned teeth could be moved into position to engage selected fingers 159. Or the fingers I59 could be arranged as break away tabs and a straight bail used.

Those familiar with keyboards will easily visualize other techniques for employing a selective lock for preventing operation of one or more preselected key buttons 139.

A keyboard used as a typewriter keyboard would also need a space bar. Provision for a space bar could be made by adding a forward projection on link 137. The space bar could be supported or guided by any convenient means so that depression of the space bar would result in the depression of the appropriate link 137 having the forward extension as described but not shown. Other function control keys such as: shift, tab, index, carriage ret um, etc., could be added as required.

It should be observed, as already noted, that the present structure provides a low silhouette. In addition, the structure is very compact from front to rear and therefore would require a minimum of space. Although the components are densely packed, the swing away feature permits easy assembly, inspection and maintenance.

While there has been shown and described what is considered at present to be the preferred embodiment of the invention, various modifications, in addition to those already suggested, will readily occur to those skilled in this and allied arts. It is believed that no further analysis or description is required and that the foregoing so fully reveals the gist of the present invention that those skilled in the applicable arts can adapt it to meet the exigencies of their specific requirements.

What is claimed is:

1. In a power-actuated keyboard mechanism:

a. a keylever,

b. an elongated encoding slide mounted for limited pivotal and longitudinal reciprocal motion between first and second limits,

c. bias means for biasing said slide towards said first limit of its limited pivotal and longitudinal reciprocal motion,

d. said keylever and said slide mounted in substantially parallel and side-by-side relationship,

c. said keylever pivotally supported at its ends for limited selective reciprocal motion between first and second limits in at least the pivotal direction of said limited pivotal and longitudinal reciprocal motion of said slide,

f. a projection rigidly affixed to said keylever for engaging said slide and pivoting said slide in a first direction in response to the selective actuation of said keylever towards its said second limit,

g. motion control means in cooperative relationship with said slide and responsive to the pivotal motion of said slide in said first direction for initiating the longitudinal portion of said limited pivotal and longitudinal reciprocal motion of said slide, and

h. means including said projection on said keylever acting in cooperative relationship with said slide for restricting at least part of the reciprocal longitudinal motion of said slide towards said first limit in response to the force of said bias means and when said keylever has not completed the return part of its reciprocal motion towards its said first limit.

2. The combination as set forth in claim 1 and including keylever bias means for biasing said keylever towards its second limit whereby said slide may complete its cycle of limited pivotal and longitudinal reciprocal motion when said keylever pivots in response to the force of said keylever bias means.

3. The combination as set forth in claim 1 wherein in response to the initial longitudinal motion of said slide the engagement between said slide and said projection is broken and wherein slide and said motion control means cooperate for preventing said slide biasing means from pivoting said slide towards said one limit of its pivotal motion.

4. The combination as set forth in claim 1 and including a plurality of keylevers and with each keylever having an individual associated slide.

5. The combination as set forth in claim 4 and including an interlock for preventing more than one of said slides from being pivoted away from its normal position at a time.

6. The combination as set forth in claim 5 wherein said slide includes means for opening said interlock when said slide has completed the pivotal portion of its cycle of limited pivotal and longitudinal reciprocal motion irrespective of the completion of the longitudinal portion of the cycle.

7. The combination as set forth in claim 4 wherein said motion control means comprises first and second actuating bails.

8. The combination as set forth in claim 7 wherein:

a. said slides include individual means for actuating said first bail in response to the initial pivoting of one of said slides, and wherein b. said second bail is actuated in response to the actuation of said first bail, and

c. said slide is moved longitudinally away from its said first limit in response to the actuation of said second bail.

9. The combination as set forth in claim 8 and including:

a. first bail restore means for restoring said first bail in response to the initial longitudinal motion of said slide,

b. second bail restore means for restoring said second bail in response to the restoration of said first bail, and wherein c. said slide is free to start the return part of its limited pivotal and longitudinal reciprocal motion in response to the restoration of said second bail.

10. The combination as set forth in claim 9 wherein said second bail includes locking means for locking the keylevers which are at their first limit against motion to said second limit when said second bail is actuated.

11. The combination as set forth in claim 10 and including actuating means for retaining said second bail in the actuated position when the power supply is disconnected.

12. In a keyboard mechanism:

a. a baseplate;

b. a longitudinal keylever having forward and rearward ends and which is substantially horizontal in its normal position;

c. first and second link members pivoted at their forward ends on first and second pivot rods, respectively, and pivotally coupled at their rearward ends to the forward and rearward ends, respectively, of said keylever;

d. support means mounted on said baseplate for supporting said first pivot rod;

e. a pair of arms substantially parallel to said keylever and pivoted at their forward end on a third pivot supported by said baseplate and coupled together at their rearward ends by a bar to which said second pivot rod is coupled for selectively pivoting said keylever about said first pivot when said pair pivoting arms are pivoted about said third pivot;

f. first bias means for urging said keylever towards an upper limit of its substantially horizontal normal position; and

g. a slide mounted for limited pivotal and longitudinal motion and in cooperative relationship with said keylever when said keylever is in said substantially horizontal normal position, for providing a signal responsive to the actuation of said keylever downward from said upper limit.

13. The combination as set forth in claim 12 and including:

a. second bias means for urging said slide towards one limit of its said limited pivotal and longitudinal motion;

b. slide-engaging means rigidly affixed to said keylever for engaging said slide and pivoting said slide against the force of said second bias means in response to the actuation of said keylever downward from said upper limit;

c. slide-actuating means responsive to the actuation of said keylever downward from said upper limit for cooperating with said slide and initiating a longitudinal motion of said slide against the force of said second bias means and for thereafter disengaging itselffrom said slide; and wherein d. said slide is disengaged from said slide-engaging means in response to the longitudinal motion of said slide, and

e. wherein said slide and said slide-actuating means cooperate to prevent said second bias means from pivoting said slide in response to said disengagement of said slide and said slide-engaging means.

14. The combination as set forth in claim 13 wherein said slide-engaging means limits the forward longitudinal motion of said slide which is in response to the force of said second bias means after said slide-actuating means has been disengaged from said slide and when said keylever is not at its said upper limit. t

15. The combination as set forth in claim 13 wherein said slide-actuating means comprises a bail which is actuated in response to the pivotal motion of said slide against the urging of said second bias means and which is deactivated in response to the longitudinal motion of said slide against the urging of said second bias means.

16. The combination as set forth in claim 13 wherein said slide cooperates with contact means for generating an output signal in response to said longitudinal motion of said slide against the force of said second bias means.

17. The combination as set forth in claim 13 and including a plurality of assemblies with each assembly comprising one each of said keylever, said first and second links, said slide, said first and second bias means and slide-engaging means and wherein a common slide-actuating means is used for initiating a cycle of limited pivotal and longitudinal motion of any selected one of said slides.

18. The combination as set forth in claim 17 and including interlock means for preventing the simultaneous pivoting of more than one of said slides against the urging of their respective second bias means.

19. The combination as set forth in claim 17 wherein each of said slides cooperate with contact means for generating a unique output signal in response to said longitudinal motion of said slide against the force of said second bias means.

20. The combination as set forth in claim 12 and including:

a. an upstop for limiting the upward position of said first horizontal link member.

21. in a keyboard mechanism:

a. a pivoted longitudinal keylever having a key top for manual actuation of said keylever,

b. a longitudinal slide supported for limited pivotal and longitudinal motion and in parallel side-by-side relationship with said keylever for cooperating with contact members to produce an output signal when said slide is at one limit of the longitudinal portion of its limited pivotal and longitudinal motion,

c. first bias means for biasing said keylever to one limit of its motion, I

d. second bias means for biasing said slide to the other limit of the longitudinal portion of its limited pivotal and longitudinal motion and for biasing said slide to one limit of the pivotal portion of its limited pivotal and longitudinal motion,

e. a slide-actuating ear affixed to said keylever for engaging and pivoting said slide against the force of said second bias means in response to an actuation of said keylever against its said first bias means only when said slide is at its said other limit of the longitudinal portion of its said limited pivotal and longitudinal motion and at said one limit of the pivotal portion of its said limited pivotal and longitudinal motion; and

f. a reciprocating slide-actuating bail for engaging said slide when said slide is pivoted by said slide-actuating ear and for driving said slide towards said one limit of the longitudinal portion of its limited pivotal and longitudinal motion and out of engagement with said slide-actuating ear, wherein g. said second bias means is effective to return said slide towards said other limit of the longitudinal portion of its said limited pivotal and longitudinal motion and to pivot said slide towards its said one limit of the pivotal portion of its limited pivotal and longitudinal motion in response to the return reciprocal stroke of said slide-actuating bail. and wherein at least part of the longitudinal motion of said slide towards said other limit of the longitudinal portion of its limited pivotal and longitudinal motion is restrained by said slide-actuating ear when said keylever has not been restored to its said one limit, whereby said slide is pivoted sufficiently towards its said one limit of the pivotal portion of its limited pivotal and longitudinal motion that it will not be engaged by a subsequent cycle of motion of said bail.

22. The combination as set forth in claim 21 and including a plurality of keylevers each having an associated slide.

23. The combination as set forth in claim 22 and including an interlock for preventing more than one of said slides from being pivoted against the force of their respective second bias means at a time.

24. The combination as set forth in claim 22 wherein said slide-actuating bail includes means for preventing the pivoting of any of said keylevers against the force of their respective first bias means when said actuating bail is in the position it assumes while it is holding one of said slides towards said one limit of the slide motion.

25. The combination as set forth in claim 22 and including means responsive to the pivoting of one of said keylevers against the force of its first bias means for initiating a cycle of reciprocation of said slide-actuating bail.

26. The combination as set forth in claim 22 wherein said slide and its associated slide-actuating ear on the associated keylever include means for preventing said slide from reaching said other limit of its longitudinal motion when the keylever is pivoted against its first bias means after the completion of the reciprocal motion of said slide-actuating bail. 

1. In a power-actuated keyboard mechanism: a. a keylever, b. an elongated encoding slide mounted for limited pivotal and longitudinal reciprocal motion between first and second limits, c. bias means for biasing said slide towards said first limit of its limited pivotal and longitudinal reciprocal motion, d. said keylever and said slide mounted in substantially parallel and side-by-side relationship, e. said keylever pivotally supported at its ends for limited selective reciprocal motion between first and second limits in at least the pivotal direction of said limited pivotal and longitudinal reciprocal motion of said slide, f. a projection rigidly affixed to said keylever for engaging said slide and pivoting said slide in a first direction in response to the selective actuation of said keylever towards its said second limit, g. motion control means in cooperative relationship with said slide and responsive to the pivotal motion of said slide in said first direction for initiating the longitudinal portion of said limited pivotal and longitudinal reciprocal motion of said slide, and h. means including said projection on said keylever acting in cooperative relationship with said slide for restricting at least part of the reciprocal longitudinal motion of said slide towards said first limit in response to the force of said bias means and when said keylever has not completed the return part of its reciprocal motion towards its said first limit.
 2. The combination as set forth in claim 1 and including keylever bias means for biasing said keylever towards its second limit whereby said slide may complete its cycle of limited pivotal and longitudinal reciprocal motion when said keylever pivots in response to the force of said keylever bias means.
 3. The combination as set forth in claim 1 wherein in response to the initial longitudinal motion of said slide the engagement between said slide and said projection is broken and wherein slide and said motion control means cooperate for preventing said slide biasing means from pivoting said slide towards said one limit of its pivotal motion.
 4. The combination as set forth in claim 1 and including a plurality of keylevers and with each keylever having an individual associated slide.
 5. The combination as set forth in claim 4 and including an interlock for preventing more than one of said slides from being pivoted away from its normal position at a time.
 6. The combination as set forth in claim 5 wherein said slide includes means for opening said interlock when said slide has completed the pivotal portion of its cycle of limited pivotal and longitudinal reciprocal motion irrespective of the completion of the longitudinal portion of the cycle.
 7. The combination as set forth in claim 4 wherein said motion control means comprises first and second actuating bails.
 8. The combination as set forth in claim 7 wherein: a. said slides include individual means for actuating said first bail in response to the initial pivoting of one of said slides, and wherein b. said second bail is actuated in response to the actuation of said first bail, and c. said slide is moved longitudinally away from its said first limit in response to the actuation of said second bail.
 9. The combination as set forth in Claim 8 and including: a. first bail restore means for restoring said first bail in response to the initial longitudinal motion of said slide, b. second bail restore means for restoring said second bail in response to the restoration of said first bail, and wherein c. said slide is free to start the return part of its limited pivotal and longitudinal reciprocal motion in response to the restoration of said second bail.
 10. The combination as set forth in claim 9 wherein said second bail includes locking means for locking the keylevers which are at their first limit against motion to said second limit when said second bail is actuated.
 11. The combination as set forth in claim 10 and including actuating means for retaining said second bail in the actuated position when the power supply is disconnected.
 12. In a keyboard mechanism: a. a baseplate; b. a longitudinal keylever having forward and rearward ends and which is substantially horizontal in its normal position; c. first and second link members pivoted at their forward ends on first and second pivot rods, respectively, and pivotally coupled at their rearward ends to the forward and rearward ends, respectively, of said keylever; d. support means mounted on said baseplate for supporting said first pivot rod; e. a pair of arms substantially parallel to said keylever and pivoted at their forward end on a third pivot supported by said baseplate and coupled together at their rearward ends by a bar to which said second pivot rod is coupled for selectively pivoting said keylever about said first pivot when said pair pivoting arms are pivoted about said third pivot; f. first bias means for urging said keylever towards an upper limit of its substantially horizontal normal position; and g. a slide mounted for limited pivotal and longitudinal motion and in cooperative relationship with said keylever when said keylever is in said substantially horizontal normal position, for providing a signal responsive to the actuation of said keylever downward from said upper limit.
 13. The combination as set forth in claim 12 and including: a. second bias means for urging said slide towards one limit of its said limited pivotal and longitudinal motion; b. slide-engaging means rigidly affixed to said keylever for engaging said slide and pivoting said slide against the force of said second bias means in response to the actuation of said keylever downward from said upper limit; c. slide-actuating means responsive to the actuation of said keylever downward from said upper limit for cooperating with said slide and initiating a longitudinal motion of said slide against the force of said second bias means and for thereafter disengaging itself from said slide; and wherein d. said slide is disengaged from said slide-engaging means in response to the longitudinal motion of said slide, and e. wherein said slide and said slide-actuating means cooperate to prevent said second bias means from pivoting said slide in response to said disengagement of said slide and said slide-engaging means.
 14. The combination as set forth in claim 13 wherein said slide-engaging means limits the forward longitudinal motion of said slide which is in response to the force of said second bias means after said slide-actuating means has been disengaged from said slide and when said keylever is not at its said upper limit.
 15. The combination as set forth in claim 13 wherein said slide-actuating means comprises a bail which is actuated in response to the pivotal motion of said slide against the urging of said second bias means and which is deactivated in response to the longitudinal motion of said slide against the urging of said second bias means.
 16. The combination as set forth in claim 13 wherein said slide cooperates with contact means for generating an output signal in response to said longitudinal motion of said slide against the force of said second bias means.
 17. The combinatioN as set forth in claim 13 and including a plurality of assemblies with each assembly comprising one each of said keylever, said first and second links, said slide, said first and second bias means and slide-engaging means and wherein a common slide-actuating means is used for initiating a cycle of limited pivotal and longitudinal motion of any selected one of said slides.
 18. The combination as set forth in claim 17 and including interlock means for preventing the simultaneous pivoting of more than one of said slides against the urging of their respective second bias means.
 19. The combination as set forth in claim 17 wherein each of said slides cooperate with contact means for generating a unique output signal in response to said longitudinal motion of said slide against the force of said second bias means.
 20. The combination as set forth in claim 12 and including: a. an upstop for limiting the upward position of said first horizontal link member.
 21. In a keyboard mechanism: a. a pivoted longitudinal keylever having a key top for manual actuation of said keylever, b. a longitudinal slide supported for limited pivotal and longitudinal motion and in parallel side-by-side relationship with said keylever for cooperating with contact members to produce an output signal when said slide is at one limit of the longitudinal portion of its limited pivotal and longitudinal motion, c. first bias means for biasing said keylever to one limit of its motion, d. second bias means for biasing said slide to the other limit of the longitudinal portion of its limited pivotal and longitudinal motion and for biasing said slide to one limit of the pivotal portion of its limited pivotal and longitudinal motion, e. a slide-actuating ear affixed to said keylever for engaging and pivoting said slide against the force of said second bias means in response to an actuation of said keylever against its said first bias means only when said slide is at its said other limit of the longitudinal portion of its said limited pivotal and longitudinal motion and at said one limit of the pivotal portion of its said limited pivotal and longitudinal motion; and f. a reciprocating slide-actuating bail for engaging said slide when said slide is pivoted by said slide-actuating ear and for driving said slide towards said one limit of the longitudinal portion of its limited pivotal and longitudinal motion and out of engagement with said slide-actuating ear, wherein g. said second bias means is effective to return said slide towards said other limit of the longitudinal portion of its said limited pivotal and longitudinal motion and to pivot said slide towards its said one limit of the pivotal portion of its limited pivotal and longitudinal motion in response to the return reciprocal stroke of said slide-actuating bail, and wherein at least part of the longitudinal motion of said slide towards said other limit of the longitudinal portion of its limited pivotal and longitudinal motion is restrained by said slide-actuating ear when said keylever has not been restored to its said one limit, whereby said slide is pivoted sufficiently towards its said one limit of the pivotal portion of its limited pivotal and longitudinal motion that it will not be engaged by a subsequent cycle of motion of said bail.
 22. The combination as set forth in claim 21 and including a plurality of keylevers each having an associated slide.
 23. The combination as set forth in claim 22 and including an interlock for preventing more than one of said slides from being pivoted against the force of their respective second bias means at a time.
 24. The combination as set forth in claim 22 wherein said slide-actuating bail includes means for preventing the pivoting of any of said keylevers against the force of their respective first bias means when said actuating bail is in the position it assumes while it is holding one of said slides towards said one limit of the slide motion.
 25. The combinAtion as set forth in claim 22 and including means responsive to the pivoting of one of said keylevers against the force of its first bias means for initiating a cycle of reciprocation of said slide-actuating bail.
 26. The combination as set forth in claim 22 wherein said slide and its associated slide-actuating ear on the associated keylever include means for preventing said slide from reaching said other limit of its longitudinal motion when the keylever is pivoted against its first bias means after the completion of the reciprocal motion of said slide-actuating bail. 